use core::clone::Clone;
use core::cmp::{Eq, PartialEq};
use core::fmt::Debug;
use core::fmt::{self, Write};
use core::marker::Copy;
use core::ops::{Deref, DerefMut};
use core::prelude::rust_2024::derive;
use lazy_static::{ lazy_static};
use volatile::Volatile;


#[allow(dead_code)]
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
#[repr(u8)]
pub enum Color {
    Black = 0,
    Blue = 1,
    Green = 2,
    Cyan = 3,
    Red = 4,
    Magenta = 5,
    Brown = 6,
    LightGray = 7,
    DarkGray = 8,
    LightBlue = 9,
    LightGreen = 10,
    LightCyan = 11,
    LightRed = 12,
    Pink = 13,
    Yellow = 14,
    White = 15,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(transparent)]
pub struct ColorCode(u8);
impl ColorCode {
    fn new(frontgroud: Color, backgroupd: Color) -> Self {
        Self((frontgroud as u8) << 4 | backgroupd as u8)
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(C)]
struct ScreenChar {
    ascii_character: u8,
    color_code: ColorCode,
}

const BUFFER_HEIGHT: usize = 25;
const BUFFER_WIDTH: usize = 80;

#[repr(transparent)]
struct Buffer {
    chars: [[Volatile<ScreenChar>; BUFFER_WIDTH]; BUFFER_HEIGHT],
}

pub struct Writer {
    column_position: usize,
    color_code: ColorCode,
    buffer: &'static mut Buffer,
}

impl Write for Writer {
    fn write_str(&mut self, s: &str) -> fmt::Result {
        self.write_string(s);
        Ok(())
    }
}
impl Deref for ScreenChar{
    type Target = Self;
    fn deref(&self) -> &Self::Target {
        self
    }
}
impl DerefMut for ScreenChar{
    fn deref_mut(&mut self) -> &mut Self::Target {
        self
    }
}

impl Writer {
    pub fn write_byte(&mut self, byte: u8) {
        match byte {
            b'\n' => self.new_line(),
            byte => {
                if self.column_position >= BUFFER_WIDTH {
                    self.new_line();
                }
                let row = BUFFER_HEIGHT - 1;
                let column = self.column_position;
                let char_color = self.color_code;
                let char = ScreenChar {
                    ascii_character: byte,
                    color_code: char_color,
                };
                self.buffer.chars[row][column] = Volatile::new(char);
                self.column_position += 1;
            }
        }
    }
    fn new_line(&mut self) {
        for row in 1..BUFFER_HEIGHT {
            for col in 0..BUFFER_WIDTH {
                let character = self.buffer.chars[row][col].read();
                self.buffer.chars[row - 1][col].write(character);
            }
        }
        self.clear_line(BUFFER_HEIGHT - 1);
        self.column_position = 0;
    }
    fn clear_line(&mut self, line_index: usize) {
        let blank_char = ScreenChar {
            ascii_character: b' ',
            color_code: self.color_code,
        };
        for col in 0..BUFFER_WIDTH {
            self.buffer.chars[line_index][col].write(blank_char);
        }
    }
    pub fn write_string(&mut self, s: &str) {
        for b in s.bytes() {
            match b {
                0x20..0x70 | b'\n' => {
                    self.write_byte(b);
                }
                _ => {
                    self.write_byte(0xfe);
                }
            }
        }
    }
}

use spin::Mutex;
lazy_static! {
    pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
        column_position: 0,
        color_code: ColorCode::new(Color::Red, Color::Green),
        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
    });
}

#[doc(hidden)]
pub fn _print(args:fmt::Arguments){
    WRITER.lock().write_fmt(args).unwrap();
}

#[macro_export]
macro_rules! print {
    ($($arg:tt)*) => {
        $crate::vga_buffer::_print(format_args!($($arg)*));
    };
}

#[macro_export]
macro_rules! println {
    () => {
        $crate::print!("\n");
    };
    ($($arg:tt)*) => {
        $crate::print!("{}\n",format_args!($($arg)*));
    };
}
